In a non-randomised extension study in patients with kidney disease [47] where treatment duration (up to 43 weeks) depended on the degree of anaemia, IV ferric carboxymaltose resulted in a mean Hb increase of 19 g/L and clinical success (Hb ≥100 g/L, ferritin 100-800 μg/L, TSAT 30-50%) of 72/140 (51%). This evidence concerns the gene GSTM1 and anemia (phenotype).